Beam steering device and system including the same

ABSTRACT

Provided are a beam steering device and a system including the same. The beam steering device includes a conversion layer having a refractive index which is variable via electrical control and a plurality of nanoantenna pattern layers stacked on the conversion layer. The refractive index of the conversion layer is electrically changed by a driver.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2015-0167506, filed on Nov. 27, 2015, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

1. Field

Apparatuses and systems consistent with exemplary embodiments relate toa beam steering device capable of steering a beam in a non-mechanicalmanner and a system including the beam steering device.

2. Description of the Related Art

In a mechanical beam steering device, a beam emission part ismechanically rotated, via a motor or the like, in order to steer a beamto a desired location. In other words, light emitted from a laser diodeor a light-emitting diode, for example, is steered by a rotation of anentire beam emission part. Since a motor or the like must be included ina mechanical beam steering system, the volume and cost of such asteering system is high and the system may be quite noisy due to the useof the motor. One example of a non-mechanical beam steering systemincludes a microelectromechanical system (MEMS) mirror. However, a MEMSmirror-based non-mechanical beam steering system has a narrow field ofemission, and when high-power light is emitted, a transfer distance ofthe light may be short due to stress applied to the mirror.

SUMMARY

One or more exemplary embodiments may provide a beam steering devicewhich steers a beam in a non-mechanical manner and has improved beamdirectivity and a system including the beam steering device.

Additional exemplary aspects and advantages will be set forth in part inthe description which follows and, in part, will be apparent from thedescription, or may be learned by practice of the presented exemplaryembodiments.

According to an aspect of an exemplary embodiment, a beam steeringdevice includes: a conversion layer of which refractive index isvariable via electrical control; a driver configured to electricallychange the refractive index of the conversion layer; and a plurality ofnanoantenna pattern layers stacked on the conversion layer.

The beam steering device may further include a reflective mirror layerbetween the conversion layer and the driver.

The conversion layer may be between the reflective mirror layer and theplurality of nanoantenna pattern layers.

An insulating material may be filled between the conversion layer andthe reflective mirror layer.

The reflective mirror layer may include a metal pattern layer.

An insulating material may be filled between metal patterns of thereflective mirror layer.

The reflective mirror layer may be overall formed of a metal material.

The reflective mirror layer and the plurality of nanoantenna patternlayers may be formed of a same metal material.

An insulating layer may be between the plurality of nanoantenna patternlayers such that the plurality of nanoantenna pattern layers are spacedapart from each other.

The plurality of nanoantenna pattern layers may include: an uppernanoantenna pattern layer located at an uppermost layer; and at leastone lower nanoantenna pattern layer, wherein an insulating material isfilled between nanoantenna patterns of the at least one lowernanoantenna pattern layer.

Each of the plurality of nanoantenna pattern layers may include aplurality of nanoantenna elements arranged in an array in each unitcell.

The plurality of nanoantenna elements may have a same size in each unitcell.

A size of the nanoantenna elements may vary for each unit cell.

Each of the plurality of nanoantenna pattern layers may include at leastone selected from the group consisting of gold (Au), silver (Ag),titanium nitride (TiN), tantalum nitride (TaN), platinum (Pt), aluminum(Al), and an alloy thereof.

The conversion layer may include an oxide semiconductor material.

The conversion layer may include at least one of indium tin oxide (ITO),indium zinc oxide (IZO), gallium indium zinc oxide (GIZO), zinc oxide(ZnO), aluminum zinc oxide (AZO), and gallium zinc oxide (GZO).

A size of nanoantenna elements and a gap between the nanoantennaelements in each of the plurality of nanoantenna pattern layers may beless than a wavelength of a beam incident on the plurality ofnanoantenna pattern layers.

According to an aspect of another exemplary embodiment, a systemincludes: a beam steering device configured to steer an incident beamsuch that the incident beam is reflected at a desired angle and havingthe features described above; a driving circuit configured toelectrically change the refractive index of the conversion layer of thebeam steering device; and a light source configured to emit the incidentbeam to the beam steering device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other exemplary aspects and advantages will become apparentand more readily appreciated from the following description of exemplaryembodiments, taken in conjunction with the accompanying drawings inwhich:

FIGS. 1, 2, and 3 each illustrate a structure of a beam steering device,according to an exemplary embodiment;

FIG. 4 illustrates an arrangement of a plurality of nanoantenna elementsin a beam steering device, according to an exemplary embodiment;

FIG. 5 illustrates an arrangement of a plurality of nanoantenna elementsin a beam steering device, according to another exemplary embodiment;

FIG. 6 illustrates an operation of a beam steering device, according toan exemplary embodiment;

FIG. 7 illustrates a change in a phase shift amount for each pixel; and

FIG. 8 illustrates a system including a beam steering device, accordingto an exemplary embodiment.

DETAILED DESCRIPTION

A beam steering device and a system employing the same according toexemplary embodiments will now be described in detail with reference tothe accompanying drawings. In the drawings, like reference numeralsrefer to like elements, and the sizes and thicknesses of components maybe exaggerated for convenience of description. In this regard, theexemplary embodiments may have different forms and should not beconstrued as being limited to the descriptions set forth herein.Accordingly, the embodiments are merely exemplary descriptions,referring to the figures, used to explain various aspects. In thedescription below, when it is described that a certain layer is provided“on”, “on an upper part of”, or “above” a substrate or another layer,the certain layer may be in direct contact with and above the substrateor another layer, or a third layer may be interposed therebetween. Asused herein, expressions such as “at least one of,” when preceding alist of elements, modify the entire list of elements and do not modifythe individual elements of the list.

FIGS. 1, 2, and 3 illustrate structures of beam steering devices 100,200, and 300, respectively, according to exemplary embodiments. The beamsteering device 200 of FIG. 2 differs from the beam steering devices 100and 300 of FIGS. 1 and 3 in the structure of a reflective mirror layer30. The beam steering device 300 of FIG. 3 differs from the beamsteering devices 100 and 200 of FIGS. 1 and 2 in a number of stacks ofnanoantenna pattern layers 70 and 90.

Referring to FIGS. 1 through 3, each of the beam steering devices 100,200 and 300 includes a conversion layer 40 which comprises a refractiveindex which is variable via electrical control, the plurality ofnanoantenna pattern layers 70 and 90 stacked on the conversion layer 40,and a driver 20 configured to electrically change the refractive indexof the conversion layer 40. In the beam steering devices 100, 200 and300, the driver 20, the conversion layer 40, and the plurality ofnanoantenna pattern layers 70 and 90 may be stacked in order. Areflective mirror layer 30 may be further included between theconversion layer 40 and the driver 20. FIGS. 2 and 3 show examples inwhich the reflective mirror layer 30 is formed as a pattern layer 31.

The stacked structures of FIGS. 1 through 3 illustrate unit cells of thebeam steering devices 100, 200 and 300, respectively, and each of thebeam steering devices 100, 200 and 300 may have a form in which aplurality of the stack structures are arranged in an array.

The conversion layer 40 may include a transparent oxide semiconductormaterial, e.g., a transparent conductive material, having a refractiveindex is changeable according to an applied voltage. For example, theconversion layer 40 may include at least one of indium tin oxide (ITO),indium zinc oxide (IZO), gallium indium zinc oxide (GIZO), zinc oxide(ZnO), aluminum zinc oxide (AZO), and gallium zinc oxide (GZO).

When charge accumulation in the conversion layer 40 is controlled by anapplied voltage, the refractive index of the conversion layer 40 may bechanged, and accordingly, beam steering using a metasurface may beperformed.

The plurality of nanoantenna pattern layers 70 and 90 may each comprisea metal material so that beam steering using a metasurface may beachieved and so that the devices have structures including a pluralityof stacked layers. As such, when the nanoantenna pattern layers 70 and90 are stacked in a plurality of layers, directivity is improved,thereby maximizing the intensity of a beam steered to a certainlocation. As another example, the plurality of nanoantenna patternlayers 70 and 90 may include a dielectric material.

The plurality of nanoantenna pattern layers 70 and 90 may include, forexample, an upper nanoantenna pattern layer 90, disposed as theuppermost layer, and a lower nanoantenna pattern layer 70, disposedbetween the upper nanoantenna pattern layer 90 and the conversion layer40. As shown in FIGS. 1 and 2, the plurality of nanoantenna patternlayers 70 and 90 may include two nanoantenna pattern layers, wherein thelower nanoantenna pattern layer 70 is a single layer. However, theplurality of nanoantenna pattern layers 70 and 90 may include three ormore nanoantenna pattern layers in a stacked form in which the lowernanoantenna pattern layer 70 includes two or more layers. FIG. 3illustrates the beam steering device 300 in which the plurality ofnanoantenna pattern layers 70 and 90 includes three layers, according toan exemplary embodiment, in which the lower nanoantenna pattern layer 70includes two nanoantenna pattern layers 75 and 77.

The upper nanoantenna pattern layer 90, disposed as the uppermost layer,may correspond to a director antenna. By also including the lowernanoantenna pattern layer 70, the directivity of the beam steeringdevices 100, 200 and 300 may be improved. The reflective mirror layer 30may be patterned and used as a reflector.

Each of the nanoantenna pattern layers 70 and 90 may be formed using ametal material. For example, each of the nanoantenna pattern layers 70and 90 may include at least one selected from the group consisting ofgold (Au), silver (Ag), titanium nitride (TiN), tantalum nitride (TaN),platinum (Pt), aluminum (Al), and an alloy thereof.

Each of the nanoantenna pattern layers 70 and 90 may include a pluralityof nanoantenna elements 71 or 91, disposed in an array in each unitcell. Although FIGS. 1 through 3 show that five nanoantenna elements 71or 91 are provided in each layer in a single unit cell, this is onlyillustrative, and the number of nanoantenna elements 71 or 91 arrangedin each unit cell may be variously modified.

The plurality of nanoantenna elements 71 or 91 may have the same size.Alternately, the size of the plurality of nanoantenna elements in oneunit cell may be different from the size of the plurality of nanoantennaelements in a different unit cell. For example, as shown in FIG. 4, theplurality of nanoantenna elements 71 or 91 may have the same shape andsize in all unit cells 110. Alternatively, as shown in FIG. 5, theplurality of nanoantenna elements 71 or 91 in each unit cell may havethe same shape and size within the unit cell, but the size and shape ofthe plurality of nanoantenna elements in one unit cell 110 may differfrom the size and/or shape of the plurality of nanoantenna elements inother unit cells. The size and/or shape of the plurality of nanoantennaelements 71 or 91 may gradually decrease or increase from one unit cellto another within an array of unit cells, as shown in FIG. 5.

Although FIGS. 4 and 5 show that the plurality of nanoantenna elements71 or 91 are rectangular, the plurality of nanoantenna elements 71 or 91may be formed in a circular, oval, polygonal or irregular shape instead.In addition, the plurality of nanoantenna elements 71 or 91 may bealigned such that arrays of the elements include certain gaps or mayhave irregularly arranged patterns or arrays.

The nanoantenna elements 71 or 91 may have different sizes according towhich of the plurality of nanoantenna pattern layers 70 and 90 they arein. For example, a size of the nanoantenna elements 91 located in theupper nanoantenna pattern layer 90 may be smaller than a size of thenanoantenna elements 71 located in the lower nanoantenna pattern layer70. When the lower nanoantenna pattern layer 70 includes two or morelayers, the size of the nanoantenna elements 71 may gradually decreasefrom the lowest of the layers toward the upper nanoantenna pattern layer90. As another example, the plurality of nanoantenna pattern layers 70and 90 may include the nanoantenna elements 71 or 91 having the samesize regardless of which layer they are in. That is, the nanoantennaelements 71 or 91 located in the plurality of nanoantenna pattern layers70 and 90 may have a same size regardless of locations in a depthdirection of the beam steering devices 100, 200 and 300, or they mayhave sizes which gradually decrease or increase from the lowest layer tothe uppermost layer.

The size of the nanoantenna elements 71 or 91 in each unit cell 110 ofthe plurality of nanoantenna pattern layers 70 and 90 and the gapbetween the nanoantenna elements 71 and 91 may be smaller than awavelength of a beam incident on the plurality of nanoantenna patternlayers 70 and 90, i.e., a beam to be steered. For example, the size andgap of the nanoantenna elements 71 and 91 may be about a half or onethird or less of the wavelength of the beam to be steered. The size andgap of the nanoantenna elements 71 and 91 may vary within a range inwhich each of the beam steering devices 100, 200, and 300, according toan exemplary embodiment, steers a beam to a desired location byreflecting and diffracting the beam with desired optical efficiency.

Referring back to FIGS. 1 through 3, an insulating layer 50 may beformed between the plurality of nanoantenna pattern layers 70 and 90such that the plurality of nanoantenna pattern layers 70 and 90 arespaced apart from each other. The insulating layer 50 may also be formedbetween the lower nanoantenna pattern layer 70 and the conversion layer40. In addition, an insulating material 50 a may be filled between thenanoantenna elements 71 of the lower nanoantenna pattern layer 70, suchthat the nanoantenna elements 71 of the lower antenna pattern layer 70are each surrounded by insulating material.

The insulating layer 50 between the plurality of nanoantenna patternlayers 70 and 90 and between the lower nanoantenna pattern layer 70 andthe conversion layer 40 and the insulating material 50 a filled betweenthe nanoantenna elements 71 of the lower nanoantenna pattern layer 70may include the same material or two or more different materials.

The insulating layer 50 between the plurality of nanoantenna patternlayers 70 and 90 and the insulating material 50 a filled between thenanoantenna elements 71 may include at least one of various types ofinsulating materials, e.g., aluminum oxide (Al₂O₃), hafnium oxide(HfO₂), zirconium oxide (ZrO₂), silicon oxide (SiO₂), and siliconnitride (SiN₄).

The reflective mirror layer 30 is configured to improve the opticalefficiency of the beam steering devices 100, 200, and 300 by reflectingan incident beam and may include a metal material. The reflective mirrorlayer 30 may include a metal pattern layer 31 as shown in FIGS. 2 and 3.For example, an insulating material 35 may be filled between metalpatterns of the metal pattern layer 31. Alternately, the reflectivemirror layer 30 may include a simple metal layer without a pattern asshown in FIG. 1.

The reflective mirror layer 30 may include the same metal material asthat of the plurality of nanoantenna pattern layers 70 and 90.Alternatively, the reflective mirror layer 30 may include a metalmaterial which is different from that of the plurality of nanoantennapattern layers 70 and 90.

The reflective mirror layer 30 is configured to act as an electrode forthe conversion layer 40. That is, when a voltage controlled by thedriver 20 through the reflective mirror layer 30 is applied to theconversion layer 40, charge accumulation in the conversion layer 40 mayvary, thereby changing the refractive index of the conversion layer 40.

As shown in FIGS. 2 and 3, the reflective mirror layer 30 may includethe metal pattern layer 31 and may be patterned to correspond to theplurality of nanoantenna pattern layers 70 and 90, thereby alsofunctioning as an additional nanoantenna pattern layer.

In the beam steering devices 100, 200, and 300 as shown in FIGS. 1through 3, the driver 20 is configured to apply a voltage to theconversion layer 40 so as to change refractive index of the conversionlayer 40 according to a change in the charge accumulation in theconversion layer 40. The driver 20 may include one transistor and onecapacitor. A driving circuit 10 including the driver 20 may include adigital-to-analog converter (DAC) for applying a voltage to a cell arrayincluding the driver 20 including one transistor and one capacitor, anda scanner or a selector for selecting a certain column. The driver 20 ineach unit cell may include a capacitor, which is a storage space, and atransistor for writing a certain voltage by accessing the capacitor. Anupper plate of the capacitor in each cell may be one-to-one connected toeach unit cell of the beam steering devices 100, 200, and 300 to drivethe conversion layer 40 of each unit cell 110 of the beam steeringdevices 100, 200, and 300 by the voltage stored in the capacitor.

At a first time, voltages of a certain pattern may be written in aplurality of cells of the driving circuit 10 to drive the cell array inthe beam steering device 100, 200, or 300 in a pattern configured forbeam steering at a certain angle, and at a second time, voltages of achanged pattern may be written to drive the cell array in the beamsteering device 100, 200, or 300 in a pattern configured for beamsteering at a second angle, and such operations may be repeated torotate a beam.

FIG. 6 illustrates an operation of the beam steering device 100, 200, or300, according to an exemplary embodiment.

As shown in FIG. 6, when a beam is incident on the beam steering device100, 200, or 300, the beam steering device 100, 200, or 300 reflects thebeam at a certain angle. In this case, a traveling direction of thereflected beam may vary according to the voltage input to the conversionlayer 40. When the driver 20 controls charge accumulation in theconversion layer 40, the refractive index of the conversion layer 40 ischanged. The incident beam is reflected from the plurality ofnanoantenna pattern layers 70 and 90 according to the value of thechanged refractive index and is emitted at a desired angle.

As a voltage applied to the conversion layer 40 of the beam steeringdevice 100, 200, or 300 increases, the charge accumulation in theconversion layer 40 increases, and as the charge accumulation increases,the amount of phase shift applied to the beam reflected from theplurality of nanoantenna pattern layers 70 and 90 also increases. Thephase shift amount may vary in proportion to the charge accumulation onthe conversion layer 40. The plurality of nanoantenna pattern layers 70and 90 diffract and reflect the incident beam, and in this case, areflected diffraction angle may be controlled by adjusting a phase shiftamount according to the change in the refractive index of the conversionlayer 40 for each pixel.

FIG. 7 illustrates a change in a phase shift amount for each of aplurality of pixels.

As shown in FIG. 7, a traveling direction of a beam, i.e. the directionin which the beam is reflected, may be determined by increasing ordecreasing the phase of each pixel by a certain amount. In this case,the traveling direction of a beam may be changed according to the changeof the phase of the pixel from which the beam is reflected.

Therefore, a diffraction angle may be changed by adjusting the phaseshift amount.

Thus, using the beam steering devices 100, 200, and 300 according toexemplary embodiments, beam directivity may be changed according tovarious arrangements of the nanoantenna elements 71 and 91 stacked in aplurality layers.

For example, as compared to an arrangement in which a single nanoantennaelement 71 or 91 is included in each of three layers, an arrangement inwhich a 2×2 array of nanoantenna elements 71 or 91 is included in eachlayer may provide improved directivity. As compared to the arrangementof the 2×2 array of nanoantenna elements included in each layer, anarrangement in which a 3×3 array of nanoantenna elements is included ineach layer may also provide improved directivity.

According to exemplary embodiments, each of the beam steering devices100, 200, and 300 have a structure in which the plurality of nanoantennapattern layers 70 and 90 are stacked, and, in each unit cell, each ofthe plurality of nanoantenna pattern layers includes an arrangement ofan m×n array of nanoantenna elements 71 or 91 (where each of m and n isan integer of 2 or more), and thus, beam directivity may besignificantly improved.

Although the beam steering devices 100, 200, and 300 according toexemplary embodiments have been described by illustrating the structuresshown in FIGS. 1 through 5, the exemplary embodiments are not limitedthereto. The exemplary embodiments are only illustrative and may bevariously modified.

FIG. 8 illustrates a system employing a beam steering device 500,according to an exemplary embodiment.

Referring to FIG. 8, the system employing the beam steering device 500,according to an exemplary embodiment, may be utilized as, for example, asolid state meta light detection and ranging (LiDAR) system and mayinclude the beam steering device 500 in a meta-photonic chip form, thedriving circuit 10, and a light source 600. The beam steering device 500may be configured as any one of the beam steering devices 100, 200, and300 according to exemplary embodiments.

The light source 600 may be, for example, a laser light source such as alaser diode or a light source such as a light-emitting diode, thoughthese are merely examples, and any of various light sources may be used.When a laser light source is used for the light source 600, the beamsteering device 500 steers a laser beam toward a desired location.

The beam steering device 500 and the system employing the same accordingto the present exemplary embodiment have structures in which theplurality of nanoantenna pattern layers 70 and 90 are stacked, and thus,beam reflection efficiency and beam directivity toward a desiredlocation may be significantly improved, and a beam directivitycharacteristic may be further improved by adjusting the sizes of and thegaps between and among the nanoantenna elements 71 and 91.

In addition, the beam steering device 500 and the system employing thesame according to exemplary embodiments may have improved beamdirectivity characteristics, and thus, any optical system portion usedfor preventing beam spread may be minimized or removed, therebysimplifying the system.

According to one or more exemplary embodiments, a beam steering deviceincludes a conversion layer having a refractive index is variable viaelectrical control and a plurality of nanoantenna pattern layers stackedon the conversion layer, and thus, a beam steering device and a systemin which a beam is steered in a non-mechanical manner, i.e., anelectrical control manner, with significantly improved beam reflectionefficiency and beam directivity toward a desired location may berealized.

A beam steering device and a system employing the same according to oneor more exemplary embodiments may provide improved beam directivitycharacteristics, and thus any optical system portion used for preventingbeam spread may be minimized or removed, thereby simplifying the system.

It should be understood that exemplary embodiments described hereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more exemplary embodiments have been described withreference to the figures, it will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope as defined by thefollowing claims.

What is claimed is:
 1. A beam steering device comprising: a conversionlayer comprising a material with a refractive index which is variablevia electrical control; a driver configured to electrically change therefractive index of the conversion layer; a plurality of nanoantennapattern layers comprising an upper nanoantenna pattern layer and a lowernanoantenna pattern layer vertically stacked on the conversion layer,such that the lower nanoantenna pattern layer is disposed between theconversion layer and the upper nanoantenna pattern layer, wherein eachof the plurality of nanoantenna pattern layers comprises an array of aplurality of nanoantenna elements, and an insulating layer disposedbetween the upper nanoantenna pattern layer and the lower nanoantennapattern layer.
 2. The beam steering device of claim 1, furthercomprising a reflective mirror layer disposed between the conversionlayer and the driver.
 3. The beam steering device of claim 2, whereinthe conversion layer is disposed between the reflective mirror layer andthe plurality of nanoantenna pattern layers.
 4. The beam steering deviceof claim 2, further comprising an insulating material layer disposedbetween the conversion layer and the reflective mirror layer.
 5. Thebeam steering device of claim 2, wherein the reflective mirror layercomprises a metal pattern comprising an array of metal portions.
 6. Thebeam steering device of claim 5, wherein an insulating material isdisposed between adjacent metal portions in the reflective mirror layer.7. The beam steering device of claim 2, wherein the reflective mirrorlayer comprises a substantially uniform metal material.
 8. The beamsteering device of claim 2, wherein the reflective mirror layer and theplurality of nanoantenna elements each comprise a same metal material.9. The beam steering device of claim 1, further comprising an insulatinglayer disposed between the lower nanoantenna pattern layer and theconversion layer.
 10. The beam steering device of claim 1, wherein thelower nanoantenna pattern layer comprises an insulating materialdisposed between adjacent ones of the plurality of nanoantenna elements.11. The beam steering device of claim 1, comprising a plurality of unitcells, wherein in each of the plurality of unit cells, each of theplurality of nanoantenna pattern layers comprises a plurality ofnanoantenna elements.
 12. The beam steering device of claim 11, whereineach of the plurality of unit cells comprises a plurality of nanoantennaelements of a same size.
 13. The beam steering device of claim 11,wherein a size of the plurality of nanoantenna elements of a first oneof the plurality of unit cells is different from a size of the pluralityof nanoantenna elements of a second one of the plurality of unit cells.14. The beam steering device of claim 1, wherein each of the pluralityof nanoantenna pattern layers comprises at least one material selectedfrom a group consisting of gold (Au), silver (Ag), titanium nitride(TiN), tantalum nitride (TaN), platinum (Pt), aluminum (Al), and analloy of one of gold (Au), silver (Ag), titanium nitride (TiN), tantalumnitride (TaN), platinum (Pt), and aluminum (Al).
 15. The beam steeringdevice of claim 1, wherein the conversion layer comprises an oxidesemiconductor.
 16. The beam steering device of claim 1, wherein theconversion layer comprises at least one material selected form a groupconsisting of indium tin oxide (ITO), indium zinc oxide (IZO), galliumindium zinc oxide (GIZO), zinc oxide (ZnO), aluminum zinc oxide (AZO),and gallium zinc oxide (GZO).
 17. A system comprising: a beam steeringdevice comprising: a conversion layer comprising a material with arefractive index which is variable via electrical control, a driverconfigured to electrically change the refractive index of the conversionlayer, a plurality of nanoantenna pattern layers comprising an uppernanoantenna pattern layer and a lower nanoantenna pattern layervertically stacked on the conversion layer, such that the lowernanoantenna pattern layer is disposed between the conversion layer andthe upper nanoantenna pattern layer, wherein each of the plurality ofnanoantenna pattern layers comprises an array of a plurality ofnanoantenna elements, and wherein the plurality of nanoantenna patternlayers are configured to steer an incident beam such that the incidentbeam is reflected at a desired angle, and an insulating layer disposedbetween the upper nanoantenna pattern layer and the lower nanoantennapattern layer; a driving circuit, electrically connected to the driver,the driving circuit configured to electrically change the refractiveindex of the conversion layer of the beam steering device via thedriver; and a light source configured to emit the incident beam to thebeam steering device.
 18. The system of claim 17, further comprising areflective mirror layer disposed between the conversion layer and thedriver.
 19. The system of claim 18, wherein a size of each of theplurality of nanoantenna pattern elements and a spacing between adjacentones of the plurality of nanoantenna pattern elements is smaller than awavelength of the incident beam.
 20. The system of claim 17, furthercomprising an insulating layer disposed between each adjacent pair ofthe plurality of nanoantenna pattern layers, such that the plurality ofnanoantenna pattern layers are spaced apart from each other.